1. Field of the Invention
The present invention relates to electronic detection of improvised explosive devices and underground threats, and more particularly to the use of airborne electromagnetic gradiometers that use synchronous detection to image detonation cables and underground facility wiring and piping.
2. Description of Related Art
Cellphones were being used to detonate roadside improvised explosive devices (IED's) in Iraq until the US Military countered with radio jamming equipment. Then the Insurgency resorted to stringing long detonation wire pairs that were not subject to radio jamming. This has proved to be difficult to counter. If the IED's or their triggers cannot be disabled as with jamming, then the next best strategy is to detect their deployment and neutralize them before the IED can injure a passing convoy.
Primary electromagnetic (EM) waves will interact with surface-laid wires and with the wiring and piping in underground infrastructures. Such re-radiate secondary EM waves that are detectable above with an EM gradiometer.